J. Lee Nelson, autoimmunity researcher and rheumatologist

Investigating mother-child cell sharing

It feels like a broken bone that never heals, a continuous ache. Pain relievers and powerful steroids may not make a dent in the excruciating pain. Nor do they relieve the swelling and stiffness for many rheumatoid arthritis sufferers. But nature sometimes offers relief: pregnancy. Like a fog lifting, most pregnant rheumatoid arthritis patients experience life without constant pain for the first time in years.

Such transformations made Lee Nelson yearn for an explanation. What could make an autoimmune disease like rheumatoid arthritis turn off? The answer may lie in the mother-child cell transfer that happens during pregnancy.

Using the placenta as a corridor, some cells travel between mom and baby, take up guest residence in their hosts, and stick around for decades. Nelson and her interdisciplinary team study this mixing of genetically distinct individuals, known as microchimerism, to identify the good and bad consequences of these foreign cells in autoimmune diseases, transplantation, cancer and pregnancy complications.

Nelson, considered one of the world's leading researchers in this investigative frontier, has been studying the role that microchimerism plays in the initiation and remission of autoimmune diseases since 1986, the year she began her research career at the Hutchinson Center.

Scientists had assumed that a normal immune system would destroy any maternal cells lingering in a child. That thinking changed when Nelson and her team found maternal cells survived decades later in healthy adults. That work provided evidence for the idea that cells transferred from mother to fetus are stem cells or related cells, capable of becoming any type of cell, since stem cells can divide indefinitely.

She also found that maternal cells in the pancreas made insulin, suggesting they may help regenerate the diseased organ in diabetics. This finding suggests that microchimerism might one day be the crux of new therapies if the non-native cells could be coaxed to restore damaged tissues.

"We're trying to home in on treatments," Nelson said. "I would like to help alleviate suffering in some way."

Nelson also conducted the first study to look at microchimerism in an autoimmune disease. She found evidence for the involvement of adopted fetal cells in scleroderma, also known as systemic sclerosis, a life-threatening illness that makes the skin hard and thick and often attacks internal organs.

Once a lone pioneer in this young field, Nelson found "an interdisciplinary challenge that people had overlooked, and it was ripe for important questions and big leaps forward." Thanks to Nelson's work, many of those questions are being answered.